Sectional pull broach



w. J. PHANEUF 2,331,499

SECTIONAL PULL BROACH Oct. 12, 1943.

Filed Dec. 19. 1941 z/eracar may? NN S1 MggEgm N @N mmm N3 um PatentedOct. 12, 1943 UNITED isTATEs PATENT OFFICE .2,331,499 v vsEerioNvAL PULL`Bannon Wilrose J. Phaneuf, Hudson,

Mass., assigner to The La Pointe Machine Tool Company, Hudson,

Mass.,

a corporation of Maine Application December 19, 1941,.SerialNe. 423,678

`3 Claims. 29-.95'.1)

tool and, if any part of the broachvis breken,` the entire breachbecomes useless.

It is the general object ef my present invention -to provide a pullbreach made up of a plurality of sections, of which only lthe sectionwhich does the actual cutting or breaching requires to be made ofhigh-grade and expensive steel.

Another object of the invention is to provide a broach having aninexpensive safety member er breaking piece, which will give-Way andprotect the more costly breaching Section, if a breaching operation isobstructed.

My invention further relates to arrangements and combinations of partswhich will be hereinafter described and more particularly pointed out inthe appended claims.

A preferred form of the invention is shown in the drawing, in which Fig.l is a side elevation of my improved secenough'to reach entirely tionalpull broach, with certain parts broken away;

Fig. 2 is a similar side elevation but partly in section to shewinternal construction;

Fig. 3 is a view similar te Fig. 2 but showing the parts after thesafety member has been breken and pulled apart;

Fig. 4 is :i side elevation of the safety member;

Fig. 5 is a side elevation of the attaching end of the breuchingsection; and

Fig. 6 i: a partial side elevation, showing a modication te bedescribed.

Referring te Fig. 1, I have shown my improved sectional pull breach B ascomprising a pull rod Ill, a safe' y member II, and a breaching orcutting Sect/l1 11 l2.

The pul rod I Il has a Wide annular groove Id near its outer end and isadapted to be inserted in the broach holder I5 of a pull breachingmachine, where it may be detachably secured by clogs I6. The specificconstruction of the broach holder forms no part of my present invention.

The pull rod I 0 is of suchdiameter that it can be passed freely throughthe opening te be breached and it is provided at its opposite erfollowing end with an axial'` opening comprising an outer cylindricalportion 'I and-an inner threaded portion I8.x

The safety member I I issimilarly provided with an axial 'opening atvitsfollowing end comprising a cylindrical outer portion 23 and a threaded`inner portion 2l.u Atits leading end, the safety member II is extendedte provide a cylindrical pertion- 22 and a threaded portion 23,

separated vby an annular groove'd portion 2d of reduced diameter.

'l The safety member I I is adapted to be screwed rmlyinto the threadedend efthepull rod Iii, as shown in Figs. 1 and'2, with the cylindricalportion 2,2 `fitting the cylindrical opening I'I, and witht'he threadedend Y23 screwed inte` the threaded opening I8 of the pull rod.

The breaching section I2 may be of Vany desired `breaching constructionand isshewnvherein as having pilot or guide ribs 3l) and as havingbreaching or cutting units 3l, only one of which is shown in thedrawing. Any desired number of additional guiding and cutting portionsmay be used. The specic construction of the'breaching section I2 formsno part of the present invention and will vary widely for differentbroach-` ing operations. ing section is provided with an extensioncomprising a cylindrical portion 33 (Fig. 5) and a threaded portion 34,the portion 33 ntting the opening 20111 the safety member II, and thethreaded portion 34 screwing inte the threadedA j portion 2l ef .themember II. It will be noted that no annular groove separates theportions 33 and 3l! which form thev extension of th breaching sectionI2.

The parts are assembled as shown in Figs. l and 2, and are thentightened together, se that the three sections I0, II and I 2 form ineffect a single rigid breaching tool. It is clear, however, that onlythe breaching section I2 performs any cutting operation. Consequently,the pull rod IB and the safety member II may be made of soft steel or ofsome other strong but comparatively inexpensive metal, while only thebreaching section I2 requires high-grade and expensive tool l steel. l

When a breach is te be used in long tubular work, the combined length ofthe sections I0 and II may be two er more times the length ofthebreaching section I2 which does the actual cutting. Consequently, a mestsubstantial saving in high-grade and expensive tool steel is effected.

Furthermore, if the breaching operation is ob- N structed. in any way,se that an excessive strain The leading end of the broachis placed onthe broaching units, the safety mem'-v ber Il will promptly give way atthe annular grooved portion 24 by reason of its reduced diameter, asindicated in Fig. 3. The broaching section l2 will thus be freed fromthe puller head and may be removed from the Work Without injury. Thebroken threaded portion 23 is then removed from the end of the pull rodby any usual method; after which a new safety member Il is inserted andthe broach is again ready for use.

The safety member Il contains only a. small amount of inexpensivematerial and may' be cheaply and easily made in quantity, so that theexpense incurred by breakage is comparatively slight.

Consequently I have effected a double economy, first by forming a largepart of the pull broach from inexpensive material, and second by pro.-viding means to protect the expensive broaching section and for quicklyand easily reconstructing a broken broach.`

It will be obvious that the safety member may be omitted and the pullrod connected direct to the broaching section, in which case asubstantial saving in expensive metal will be eected but without thesafety feature.

As a further protection of the broach, I may form the leading vends ofthe pilot ribs 4I] (Fig. 6) with an axial bevel at one side, asindicated at 4I. These beveled ends then enter easily into previouslybreached grooves and the abrupt ends of the beveled ribs perform aclearing action, when necessary, and are very effective in removingchips and dirt from thergrooves `as the pilot ribs enter the grooves.This is particularly desirable for the ribsof intermediate pilotportions, as the preceding cutting units sometimes clog the grooves. Anannular groove 42 provides a space to receive the chips and dirtdislodged by the ribs.

Having thus described my invention and the advantages thereof, I do notwish to be limited to the details herein disclosed, otherwise than asset forth in the claims, but what I claim is:

1. A sectional pull breach comprising a pull rod, a breaching section, asafety-piece forming a connection between said pull rod and saidbroaching section, and means to detachably connect said parts to form arigid breaching tool, said safety piece having a braking portion ofdenitely and substantially restricted diameter and of less tensionalstrength and more easily broken than any other part of the breachingtool.

2. In a broach, a pilot section having a plurality of guiding ribs, andeach rib cut away on one side of its front end part to provide acircumferentially tapered entrance portion, with one side edge of theentrance portion of each rib parallel to the axis of said broach andrearwardly extended, and said ribs being thereby effective to perform aguiding and clearing action as the entrance portion of each rib enters agroove in the Work..

3. In a broach, a pilotsection having a plurality of guiding ribs, andeach rib cut away on one side of its front end `part to provide acircumferentially tapered entrance portion, with one side edge of theentrance portion of each rib parallel to the axis of said broach andrearwardly extended, and said ribs being thereby effective to perform aguiding and clearing action as the entrance portion of'each rib enters agroove in the work, and saidpilot section having an annular clearancegroove adjacent the leading ends of said guiding ribs.

WILROSE J. PHANEUF.

